B&B Electronics 3PCIOU4 - Manual - Manual (Page 46)

DIP Switch / Mode Settings
A-2 Appendix A Document Number 3PCI-0712m
2. Make sure you have RTS Control set to the correct mode: Normal for RS-
232, RS-485 Mode for RS-485. RS-422 mode works in either setting if the
mode jumpers are set correctly.
Checking the MIport Card
Using ComTest and a loopback connection, you can check the operation of your MIport
card separate from the rest of your communications system.
Note: Refer to Appendix C for information on how to install and use
ComTest
1. A loopback connection for RS-232 connects the Transmit output to the
Receive input (pins #2 & #3 on the DB-9 connector). Use connections below
to check all.
Figure 23. RS-232 Loopback w/Handshaking Connections
2. For RS-422 or 4-wire RS-485, connect the TD(A) to RD(A) and the TD(B) to
RD(B). Then use the ComTest program to send characters, and observe the
characters being received.
Figure 24. RS-232 Loopback Connector